Would you buy a mortise chisel to square off router-cut mortises?

[Greg Guarino]

I've already fielded some advice about alternatives to square (through) mortises. But for now - at least until I find out what a pain they are - I intend to try to make some.

From what I can glean so far, the chief advantage of mortise chisels seems to be their thickness; they are nice and strong for lever action. But I won't be chiseling out the whole mortise, only the corners. I'm wondering if mortise chisels have any advantage over standard bevel edge chisels for that task.

If so, would you get a chisel the full width of the mortise? Or perhaps one size narrower?

One more thing: I find myself wondering if it's not easier to get a straight, square edge if I start out with an oval mortise that is slightly less long than the finished mortise will be. Otherwise I would need to somehow chisel an edge that's exactly tangent to the semicircular edge of the routed mortise. Any thoughts?

[Leon]

Consider also that there are also square cut chisels. They cut both sides of the corner. Swingman uses/has one that looks like a conventional chisel and I have one that indexes.

His

I would advise establishing the corners with the chisel first and then using the router to cut the mortise. Then clean up with the chisel.

Mine is more intended to clean up shallow hinge mortises.

[whit3rd]

On Wednesday, April 29, 2015 at 2:15:59 PM UTC-7, Greg Guarino wrote: [about square through mortises]

If the bevel edge chisel can take a mallet blow on the handle, I'd say it's good enough for squaring a mainly-cut mortise. It's my understanding that mortise chisels are most useful for mortises that match the chisel width, because they guide in the mortise; bevel chisels are more for freehand-ish cutting, which means you can use any size that fits, but you have to guide the cuts with care.

Corner chisels are scary: how do I trust an edge, if I can't sharpen it? And, how do I get a good cut in both directions at once? One foresees a possibly protracted and unpleasant learning experience.

[John McCoy]

Greg Guarino wrote in news:mhrhkf$e6$ [e-mail]:

No - it would be a pain to use a mortise chisel to square up the end of the mortise. If you really want a special tool, the thing you're looking for is a corner chisel. A firmer chisel would be the ideal thing, but a regular bevel edge chisel is fine.

You want a chisel the same width as the mortise (in fact, if you were doing this handtool style, the width of the chisel defines the width of the mortise, and you cut your tenons to match the chisel).

There's two things to consider here. One is the mechanical locating of the tenon by the end of the mortise. For that you want to cut the end square to the sides, but if there's a little divot where the router cut goes beyond, it doesn't matter - the tenon will be located by the corners.

The other is the cosmetic. For a normal blind mortise with a shouldered tenon, you don't care what the ends of the mortise look like, because they're hidden. But in your case as I recall you have thru mortises, so the ends are exposed. In this case I think I would stop the router just a hair shy, and use the chisel to cut to the layout line.

John

[Greg Guarino]

I have gotten conflicting advice on those, even in this thread. My sharpening skills are in their infancy, but I have had a *minor* amount of success using one of those roller guides for regular chisels and plane irons. Would a person who can scarcely sharpen a regular chisel be able to use a corner chisel efficiently?

[Greg Guarino]

Well, there's some of that conflicting advice I mentioned in my reply to Leon. And the sharpening issue has been brought up elsewhere. But can I assume you have not tried corner chisels yourself?

[Greg Guarino]

Interesting. Why is that?

If you really want a special tool, the thing

OK. I just looked up "Firmer Chisel". I see they have a rectangular cross-section. Can you help me grasp why that would be better for this use?

Incidentally, I made a quick sloppy first attempt using bevel-edge chisels. One thing I noticed right away was that when I make the cut parallel to the grain, I have to be very gentle and not drive the chisel in very far or else it tends to split the wood. I'm thinking that - besides going a little at a time - I'll probably be better off making the "perpendicular-to-the-grain" cut first, then removing that small chip with the parallel-to-the-grain cut. And repeat... and repeat ...

I'm guessing now that this is why you recommend a firmer chisel. Once you get a little way in, the edges of the chisel will tend to guide it.

But in your

That's what I was thinking too. Too difficult to get the chisel exactly perfect at the edge of the semicircle, I would think.

[Sonny]

I've always understood, for cleaning up mortises, and other fine tuned cuts , one uses a paring chisel. They are supposed to be kept razor sharp, so as to use your muscle/hand pushing to do the cutting, not by striking with a mallet. Roy Underwood uses paring chisels, for these kinds of cuts and clean-ups, and often notes not to use a mallet. They should be sharp enou gh to cut with hand-pressure force.

I have several paring chisels and use them fairly often. From experience, for these kinds of cuts, a paring chisel can't be beat.

Check Ebay for Sheffield, Addis, Sorby, or Marples paring chisels and compa re pricing against other purchasing options. *I like old tools. Some year s ago, I bought 1/4", 3/8", 1/2" & 1" original Robert Sorby's for about $50 a piece.

Sonny

[John McCoy]

Greg Guarino wrote in news:mhtcgh$mpi$ [e-mail]:

A mortise chisel is heavy and unweildy compared to a bench chisel, and gives you no advantage in cutting the little wedge out of the corner.

Exactly. That said, I just use a bevel edge chisel when I need to clean up the end of a mortise...I think I have a couple of firmer chisels somewhere, but it's easier to just grab one of the set that I usually use than to go look for them.

John

[Sonny]

Check that. Should be Roy Underhill.

Sonny

[John McCoy]

Greg Guarino wrote in news:mhtcgh$mpi$ [e-mail]:

Oh, yeah, I meant to mention that. Especially if the mortise is near the end of a piece, you need to go carefully and do the cross-grain cut before the long grain to avoid splitting or blowing a chunk out the end.

Some people leave their stock long and cut the mortises, and then trim to length, to help avoid problems. I don't, but I usually don't use a mallet if I have to clean up the end of a mortise, and just hit the chisel with my palm.

BTW, I usually use two chisels - a narrow one for the cross- grain, and a wide one for the longways cut.

John

[dadiOH]

Right. So use a knife.

In your case, the only thing that matters is that the router mortice be squared at the outside and that area can be very shallow, rest of the mortice can be whatever as long as the tenon fits. I find it simpler to square up an area with a sharp knife rather than a chisel.

[Larry Blanchard]

Wouldn't it be a lot easier to just round over the tenon?

[Greg Guarino]

My design includes through tenons. But otherwise, I think you'd be right.

[Jerry Osage]

Does the design require through tenons for any reason other then just "looks" or just to prove that you can do it? If not, I would fake it and have the job done, probably in less time than it takes to hand carve just one through tenon to perfection.

Jerry O.

[Greg Guarino]

Working from memory, the answers to my question include:

Use a corner chisel Corner chisels are too hard to sharpen Use a regular bevel-edge chisel Use a firmer chisel (had to look that one up) Use a paring chisel, no mallet Use a knife Change the design "Fake" the through tenon.

... which is what I've come to expect. I could complain that my range of options - rather than being winnowed down - only *expands* when I ask a question here, but that's part of the fun, and how I learn. I know I'll need to do my own blundering about no matter what answers I get.

So keep it up. Does anyone recommend an electric carving knife? An dental drill? A laser?

I am still very interested in anyone's personal experience with a corner chisel, specifically whether a novice can keep one adequately sharp.

[Scott Lurndal]

It could be that you're overcomplicating the question. Any of the above will work just fine. Pick one and try it. Experience will guide you towards the optimal solution, in time.

It's not much more complicated than sharpening any edged tool, and much simpler than sharpening a gouge. Keep the back flat and touch up the bevel with a slipstone or a popsicle stick with self-adhesive sandpaper. Use a file if the edge is significantly damaged.

Personally, when I chop the mortise by hand, I use a mortise chisel. When I use the mortising attachement on the drill press or the GI mortiser, I clean up the flats with a sharp paring chisel, no mallet. I've never needed to clean up the ends of a mortise, even when using the horizontal mortiser where leaving a half-round gap at the end of the mortise if the tenon isn't rounded has no effect on structural integrity, indeed it leaves a bit of room for excess glue.

FWIW, I find the corner chisel more useful with shallow mortises, like those for hinges (for which the self-registering spring-loaded cleanup chisel is perfect).

[Electric Comet]

sharpening should be considered a skill learneed by novice/apprentice it can be a challenge but it's a skill that's real good to be had

i cringe when i see videos and the sparks are flying while someone "sharpens" their $200+ bowl gouge

[Larry Kraus]

It really does not matter how WE would create a mortise.

You've received lots of choices, grab some scrap and some tools, make a few mortices, and decide what works best for YOU.

[Sonny]

Sharpening small bevels: Get a small diamond file, or two. One or two flat files and one or two flat, yet, triangular files. Any small bevel can be easily and quickly honed - corner chisels, auger bits, other small applications.

I have a few small flat-triangular (clock repairman's) diamond files that I use for sharpening auger bits. Very handy, compared to other small files!

The problem with sharpening small bevels is not the sharpening tool, it's my eyeballs (focusing!), despite wearing reading glasses.

Sonny